Description

The DNSServiceBrowse() function is used to browse for service instances of a
particular service and protocol type. The sdRef argument points to an uninitialized
DNSServiceRef. If the call to DNSServiceBrowse succeeds sdRef is initialized. The flags
argument to DNSServiceBrowse() is currently unused and reserved for future use. A
nonzero value to interfaceIndex indicates DNSServiceBrowse() should do a browse on all interfaces.
Most applications will use an interfaceIndex value of 0 to perform a
browse on all interfaces. See the section “Constants for specifying an interface
index” in <dns_sd.h> for more details.

The callback function is invoked for every service instance found matching the
service type and protocol. The callback argument points to a function of
type DNSServiceBrowseReply listed above. The DNSServiceBrowse() call returns browse results asynchronously. The
service browse call can be terminated by applications with a call to
DNSServiceRefDeallocate().

The regtype parameter is used to specify the service type and protocol
(e.g. _ftp._tcp). The protocol type must be TCP or UDP. The domain
argument to DNSServiceBrowse() specifies the domain on which to browse for services.
Most applications will not specify a domain and will perform a browse
on the default domain(s). The context argument can be NULL and points
to a value passed to the callback function.

The sdRef argument passed to the callback function is initialized by DNSServiceBrowse()
call. The possible values passed to flags in the callback function are:
kDNSServiceFlagsMoreComing and kDNSServiceFlagsAdd. The kDNSServiceFlagsMoreComing value indicates to a callback that at
least one more result is immediately available. The kDNSServiceFlagsAdd value indicates that
a service instance was found. The errorCode argument will be kDNSServiceErr_NoError on
success. Otherwise, failure is indicated. The discovered service name is returned to
the callback via the serviceName argument. The regtype argument in the callback holds
the service type of the found service instance. The discovered service type
can be different from the requested service type in the browse request
when the discovered service type has subtypes. The domain argument to the
callback holds the domain name of the discovered service instance. The service type
and the domain name must be stored and passed along with the
service name to resolve a service instance using DNSServiceResolve().

Return Values

The DNSServiceBrowse function returns kDNSServiceErr_NoError on success. Otherwise, an error code defined
in <dns_sd.h> is returned to indicate an error has occurred. When an
error is returned by DNSServiceBrowse, the callback function is not invoked and the
DNSServiceRef argument is not initialized.